<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <link rel="stylesheet" href="./reset.css">
    <style>
        /* inline-block间隔 https://www.jianshu.com/p/b6fb427308ad */
        div {
            padding: 0;
            margin: 0;
        }

        html,
        body {
            height: 100%;
        }

        .header,
        .bottom {
            height: 20%;
            background: #d45f5f;
        }

        .container {
            height: 80%;
            display: flex;
        }

        .left,
        .right {
            width: 400px;
            height: 100%;
            background: #47e282;
        }

        .middle {
            height: 100%;
            flex: 1;
            background: #c6e247;
        }
    </style>
</head>

<body>
    <div class="header"></div>
    <div class="container">
        <div class="left"></div>
        <div class="middle"></div>
        <div class="right"></div>
    </div>
    <div class="bottom"></div>
</body>

</html>